PLoS One.
14(8):e0221091 (Aug 2019)
Species
composition of arbuscular mycorrhizal communities changes with elevation in the
Andes of South Ecuador
Ingeborg Haug,
Sabrina Setaro, Juan Pablo Suárez
Abstract
Arbuscular
mycorrhizal fungi (AMF) are the most prominent mycobionts of plants in the
tropics, yet little is known about their diversity, species compositions and
factors driving AMF distribution patterns. To investigate whether elevation and
associated vegetation type affect species composition, we sampled 646
mycorrhizal samples in locations between 1000 and 4000 m above sea level (masl)
in the South of Ecuador. We estimated diversity, distribution and species
compositions of AMF by cloning and Sanger sequencing the 18S rDNA (the section
between AML1 and AML2) and subsequent derivation of fungal OTUs based on 99%
sequence similarity. In addition, we analyzed the phylogenetic structure of the
sites by computing the mean pairwise distance (MPD) and the mean nearest taxon
difference (MNTD) for each elevation level. It revealed that AMF species
compositions at 1000 and 2000 masl differ from 3000 and 4000 masl. Lower
elevations (1000 and 2000 masl) were dominated by members of Glomeraceae,
whereas Acaulosporaceae were more abundant in higher elevations (3000 and 4000
masl). Ordination of OTUs with respect to study sites revealed a correlation to
elevation with a continuous turnover of species from lower to higher
elevations. Most of the abundant OTUs are not endemic to South Ecuador. We also
found a high proportion of rare OTUs at all elevations: 79–85% of OTUs occurred
in less than 5% of the samples. Phylogenetic community analysis indicated
clustering and evenness for most elevation levels indicating that both,
stochastic processes and habitat filtering are driving factors of AMF community
compositions.